9-Inch Rearend Axle Assembly - Dressed To The Nines

The final step to axle tube fitting is to remove the fixture and fully weld the axle tubes from the inside of the housing. This not only offers even more strength in the housing build, but it's also a critical step in sealing the multi-piece housing from leaks.

A different fixture is used to locate the housing for any suspension brackets that can be optionally welded on in-house at Strange. In our case, we sent Strange our Heidt's four-link brackets and measurement sheet so the crew could quickly weld the brackets on during the build-up phase, as shown.

The final welding operation is to install the housing ends specified by the customer. In our case, we're using the standard 3.150-inch units that accept the popular Torino "big bearing." Again, another fixture is used to ensure the housing ends are straight, as the brake assemblies mount to these, and to prevent distortion from the welding heat, which could cause oil leaks, poor bearing life, and brake wear issues.

Final Assembly
We're using Strange's S/S induction-hardened, CNC-machined 31-spline axles for our 9-inch build via its S/S axle kit.

These kits utilize screw-in 1/2-inch wheel studs for strength and a precision fit. The axles and studs are cleaned, and then red Loctite is applied to the threads of the axle flange and the studs themselves. Final assembly calls for tightening the studs to 85 ft-lb.

The S/S axles take standard 9-inch bearings and seals. Here the axle seal is already in place (don't forget the axle retainer if you're not using an aftermarket U-shaped version), and the Timken axle bearing is being pressed on. The axle bearing retainer, also called a lock ring or wedding ring, is pressed on separately, as it has a much tighter press fit of 0.005 inch compared to the axle bearing's 0.0015 inch.

Once the housing has sufficient time to cool from the welding operations, it is removed from the last jig and cleaned using Strange's in-house dedicated housing washing machine. From the cleaning back to the workbench, the Strange tech installs the axle vent into our housing. Without a vent (or if the vent gets clogged with dirt/debris) the pressure build up inside would force oil past the housing's seals. A paper gasket is laid in place for the differential assembly, though Strange notes RTV sealant is a viable option.

Strange does not charge extra for crating the rearend assembly. It comes secured on a well-built wooden pallet with a stapled/strapped cardboard cover for shipping. Freight can be arranged by Strange or you can use your favorite shipper-just make sure to have a couple of strong friends around when the truck shows up! Our new 9-inch arrived safely at our shop. Soon we'll add a Stainless Steel Brakes' rear disc kit to our assembly, and then mock up the rear, along with our Heidt's four-link setup in our Mustang. Stay tuned.

The already-completed center section is carefully placed over the housing studs, and flanged lock nuts are used to secure the assembly, which are tightened to 35-40 ft-lb. As is normal with a 9-inch assembly, the bottom two nuts will have to be tightened with a boxed-end wrench, so estimate the torque rating there compared to the other bolts you've tightened. Finally, the axles are slid home and secured with the aforementioned U-shaped axle retainers and new retaining hardware.